Abstract: In this paper, we describe an integrated design and management approach for building next-generation cities. This approach leverages IT technology in both the design and operational phases to optimize sustainability over a broad set of metrics while lowering costs. We call this approach a Sustainable IT Ecosystem. Our approach is based on five principles: ecosystem-scale life-cycle design; scalable and configurable infrastructure building blocks; pervasive sensing; data analytics and visualization; and autonomous control. Application of the approach is demonstrated for two case studies: an urban water infrastructure and an urban power microgrid. We conclude by discussing future opportunities to co- design and integrate these independent infrastructures, gaining further efficiencies.